The rapid and sensitive diagnosis of tuberculous meningitis by the detection of tuberculostearic acid in cerebrospinal fluid using gas chromatography-mass spectrometry with selective ion monitoring

Tuberculostearic acid (10-Methyloctadecanoic acid) is a lipid component of the mycobacterial cell wall and its presence in cerebrospinal fluid can serve as a diagnostic marker for tuberculous meningitis. Using gas chromatography-mass spectrometry with selective ion monitoring, tuberculostearic acid (TBSA) was detected in nine different mycobacterial reference strains. Analysis of derivatised cerebrospinal fluid specimens from 35 patients showed the presence of TBSA in 5/6 culture-positive samples and 0/19 negative control patients (diagnosed as bacterial or viral meningitis). In addition 4/10 clinically suspected cases of tuberculous meningitis showed the presence of TBSA in the absence of other confirmatory laboratory results. A routine method has been developed for the detection of TBSA, which allows the fast and sensitive diagnosis of tuberculous meningitis within 5 h of receiving the cerebrospinal fluid specimen, compared to the 3 to 8 weeks required to culture the bacteria.